1. Technical Field of the Invention
The present invention relates generally to aquatic, surface skimming devices, and more particularly to a safer aquatic, surface skimming device designed for use in varying water conditions.
2. Discussion of the Related Art
The beach activity of throwing flat round stones, sand dollars, or sea shells, in a manner in which causes the flat round projectile to rotate on a center axis, which can either take flight or be skipped over the surface of the water, is an ageless and timeless activity fascinating both young and old since antiquity. The airborne activity of sailing stones and sea shells has been modernized to what is now known as Frisbee throwing, that is, the gyroscopic propelling of an aerodynamically contoured plastic flying disk.
The large market for flying disks, such as frisbees, has been established because the products offer the consumer, not only fun and exercise, but a fascinating experience with the laws of gyroscopic aerodynamics which far surpass the common experience of sailing stones or shells. Though made of semi-rigid materials, they are lightweight and feature a smooth bulbous perimeter.
Most people have experienced skipping stones on the water. People enjoy the excitement of a well-skipped stone because it seems to defy natural law. However, rocks are skipped out over open water away from people. Unlike the sea shell""s successful transformation to plastic flying disk, the activity of skipping stones on the water has yet to evolve into a higher performing, practical and popular commercial alternative. One could conclude, that the success of a manufactured water skimming device, which could travel long distances on the water, would depend on the consumer experiencing a fascination with a new physical phenomena while experiencing a significant degree of security about the softness of the product.
One significant drawback of other aquatic devices is that they exhibit significant hydrodynamic drag due to a beveled or radiused lower edge. Non-gyroscopic hydrodynamic planing, such as with boats, requires a contoured leading edge and a sharp trailing edge. Previous inventors have assumed that a contour or beveled angle of some sort is desirable at the leading edge of a disk to break the water, as is proven in boat design. As seen in this previous design, radial contours between the bottom surface and side wall allow water to continue up the side wall and break loose above the normal water level, especially at moderate to slower speeds of the disk. Any bevel or radiused edge at the running surface perimeter will draw water and pull the disk down below the air water interface, thus causing drag.
Another significant drawback of these inventions is that substantial force is transferred through the leading edge of the disk when it makes contact with another person or object. Though not mentioned in these other inventions, soft or low density foam can""t be used alone to cushion the sides of the disk effectively because it is hydrodynamically unstable. Furthermore, soft foam alone squishes too easily when gripped and is too flexible for controlled throwing or passing of the disk. Using lightweight foam can limit the total weight of the disk, thus reducing momentum and subsequent distance. Also, lightweight foam has less mass and material, and therefore is not as durable. If the product wears or tears, the geometry changes and effects performance.
Still, another important drawback of the previous designs is that a pressure grip is required in throwing the disk. Because the disk is wet, often times a secure grip is difficult to achieve because shear tension between the hand and the disk develops when centrifugal forces occur in the throwing motion. These older inventions show a tapering from the center of the disk outwardly, encouraging the pressure grip of the hand to slide off the disk. Should such a disk be made of soft foam, it may be even harder to achieve a sufficient grip to maintain control during the throwing motion.
The patent to Richard G. Panse, U. S. Pat. No. 4,463.954, shows a water skimming device with a lower surface divided into two subsurfaces, a small central flat bottom surface transitioning or tapering to a more conical outer tapered surface surrounding that central bottom surface. In the various embodiments shown by Panse, the angle of taper or angle xe2x80x9calphaxe2x80x9d between the central flat bottom and the surrounding tapered wall is always less than 30 degrees. The Panse design exhibits poor hydrodynamics because water is forced to change course from the flat area to the conical area at the trail edge because the angle of change is less than 45 degrees. Also, the Panse patent states that the bottom central flat surface is small as seen in FIG. 2 of the Panse drawings, possibly 30% or less of the diameter of the entire disk. Panse teaches an operative radius ratio of 0.5 and under. Based on the weight and size of the Panse invention, the small inner flat surface cannot support the disk for very long at the rate of speed prescribed. Panse verifies this by stating that his disk will travel only 25 feet, at 16 miles per hour at initial projection. After 20 or so feet, the speed of the disk slows and then the small inner surface cannot support the overall weight, thus the disk sinks slightly, causing drag on the conical outer surface. Testing revealed that if the radius ratio is less than 0.80, then the alpha angle is too small to effect proper water release at the trailing edge of the disk, thus producing unwanted drag. In FIG. 7 of Panse, a symmetrical device as viewed from a side elevation, featuring a dual surface bottom, vertical side walls, rounded corners and no handle is shown. Panse states that the subsequent distances obtained by his invention averaged about 20 feet, with all distances less than 25 feet.
The disk of Thomas L. Clark shown in U. S. Pat. No. 4,979,922 shows a common flying disk and an insert which is placed into the flying disk to adapt it to skipping across the water. Clark rightly shows a rounded lower outside edge on the flying disk in his drawings. For aerodynamic reasons, flying disks are molded from a semi-rigid solid plastic, featuring an intentionally and purposefully rounded lower outside edge. The aerodynamics of the flying disk are enhanced by rounding this edge. Also, this edge is rounded because the user""s hand firmly rubs across this surface each time the disk is thrown in the air. If flying disks were made with sharp lower rim edges they would cut, blister, and chafe the user""s fingers when used in the air without an insert. The addition of a Clark insert into a flying disk fits up against the inside edge of the rim, therefore leaving the rounded lower outside edge unchanged. For aerodynamic lift in flight, the Clark invention also shows a classic frisbee ellipsoidal arc profile with the leading edge being substantially below the horizontal center plane of the disk, not above. Additionally, Clark does not show a significant mechanical handle grip on the top side of his flying disk. Instead, Clark""s invention shows a concave handle grip on the underside insert. The nature of Clark""s design is the adaptation of a common flying disk, like the frisbee which requires a grip on the underside. Clark also states that his disk and insert are made from lightweight substantially rigid materials. This combination is operatively and practically ineffective.
The balance of other disk designs mentioned above are for improvements to a flying disk only, each of which are hollow on the underside.
It is accordingly an object of the present invention to provide an aquatic device which will travel great distances across the surface of a body of water.
It is another object of the present invention to provide an aquatic device which will function in rough water conditions.
It is another object of the present invention to provide an aquatic device which is designed to minimize the impact force of the device.
It is yet another object of the present invention to accomplish the foregoing objects in a simple manner.
Additional objects and advantages of the present invention are apparent from the drawings and specification which follow.
The present invention improves over the related art by significantly increasing both attainable distance and stability. The present invention has a larg and continuous spherical segment on its bottom surface. Further, the radius ratio between the bottom edge radius and the periphery radius is greater than 0.80, not less than as is shown in the related art. This invention, by exhibiting a radius ratio of over 0.80, has an angle between the bottom surface and the side wall surface of greater than 20 degrees, therefore producing improved water release from the trailing edge of the device. Additionally, the present invention includes an abrupt or sharp edge between the convex bottom sphere segment and the convex side wall segment. The invention described herein, with its unique features, if thrown at comparable speeds to those indicated in the related art, will travel an average distance of 75 feet with maximum distances of over 100 feet. The present invention skims the water surface effectively because it maximizes the planing area while minimizing drag or water resistance. This invention includes a large single running surface is superior to a multi-planer running surface as shown in previous designs. Further, this single running surface is a smooth continuous convex spherical segment, having a parabolic radius of 50xe2x80x3 or more, and a chord height to length ratio of less than 0.02. While previous designs include bottom side handle grips, this grip design causes significant water flow disruption and causes poor performance. The present invention is sufficiently heavy to overcome lift and remain on the surface of the water and includes soft outer edges so as not to cause injury to an unwary person. These soft edges are required because this invention is 3 or 4 times the weight of a flying disk. Additionally, the present invention includes an impact absorption system to reduce the impact force should the device come in contact with something.
According to the present invention, the foregoing and additional objects are obtained by providing an aquatic device for skimming across the surface of a body of water which includes a centrally located body section, a bridge extending from the body section, a grip handle having an outer side wall, which extends from the bridge and is located about the periphery of the device and a convex bottom surface. The body may be curved over its entire upper surface, may be flat across its upper surface and may include a downwardly and outwardly ramped perimeter. The bridge is thin enough to allow bending, in the range of about 0.001 inches to 0.75 inches (0.00254 to 1.905 cm) and preferably about 0.125 inches to 0.75 inches (0.3175 to 1.905 cm) in thickness. The grip handle may be weighted for stability purposes and is between 0.1 and 1.5 inches (0.254 and 3.81 cm) in both thickness and in height and is preferably between 0.5 and 1.5 inches (1.27 and 3.81 cm) in both thickness and in height. The bottom surface has a parabolic radius of at least about 50 inches (127 cm) and the angle between the outer side wall and the bottom surface is between about 20 and 90 degrees. The bottom surface may be inset from the outer perimeter of the device. The outer side wall is convex and has a radius of between about 0.5 and 5 inches (1.27 and 12.7 cm). The device has an overall width to height ratio between about 4 to 1 and 24 to 1. The aquatic device is made from material such that the overall device has a composite density between 2 and 6 g/in3 (0.122 and 0.366 g/cm3). The device may be made from one material having this density or from 2 or more materials which act together to have a density in this range.